fix: add Admin Settings to NavigationTabbar (ET-194)

[johnkim-det]

Ticket

ET-194

Description

Adds "Admin Settings" to mobile navigation menu (if user has admin permissions)
Also renames "Settings" option to "User Settings"

Test Plan

• Open app in mobile mode.
• Click three-dot menu on lower right.
• User with admin permissions should see "Admin Settings" option which leads to Admin Settings page
• User without admin permissions should not see that option

Checklist

• Changes have been manually QA'd
• User-facing API changes need the "User-facing API Change" label.
• Release notes should be added as a separate file under docs/release-notes/.
  See Release Note for details.
• Licenses should be included for new code which was copied and/or modified from any external code.

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[codecov]

Codecov Report

Attention: Patch coverage is 0% with 13 lines in your changes are missing coverage. Please review.

Project coverage is 43.44%. Comparing base (cdd7a82) to head (e451698).
Report is 3 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #9423      +/-   ##
==========================================
- Coverage   48.61%   43.44%   -5.18%     
==========================================
  Files        1233      909     -324     
  Lines      158972   119056   -39916     
  Branches     2778     2778              
==========================================
- Hits        77278    51718   -25560     
+ Misses      81520    67164   -14356     
  Partials      174      174              

Flag	Coverage Δ
harness	?
web	44.38% <0.00%> (-0.01%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
webui/react/src/components/NavigationTabbar.tsx	0.00% <0.00%> (ø)

... and 324 files with indirect coverage changes

[keita-determined]

LGTM